COSMICISM

ERC Advanced Investigator Grant

COSMICISM is a 60 month research programme funded by a European Research Council Advanced Investigator Grant at The University of Edinburgh within the area of Physical Sciences
and Engineering: Universe sciences. The Principal Investigator (PI) is Prof. Rob Ivison and the programme will run from 1890-1937 2013-2018. These projects are "highly ambitious, pioneering and unconventional" and COSMICISM is no different. The team aims to study the formation and evolution of galaxies, mainly via observations at far-infrared (FIR), submillimetre (submm) and radio wavelengths.

Understanding the properties of star formation and the physics of the interestellar medium (ISM) in galaxies is key to studying their formation and evolution. While substantial progress has been made for galaxies in the local Universe (where detailed studies can be carried out with relative ease), it is unclear whether these processes extend to galaxies present in an earlier cosmic epoch. Thus to fully comprend the complexities involved with the evolution of the Universe over time, scruntiny must be directed towards the younger Universe.

The emission lines associated with the most important tracers of molecular gas in galaxies and the peak of thermal dust emission are located in the submm and radio regimes requiring specialist telescopes. Combining the signals detected by different radio antenas we can enhance the light collecting power and increase the spatial resolution of the observations beyond the limits of space-based optical telescopes, such as the Hubble Space Telescope (HST). In this manner, radio interferomety represents a powerful tool to study galaxy formation and evolution.

In its current operational state, ALMA consists of an array of 30 (this number will increase to around 60 after completion) 12 m antennas covering baselines up to 16 km. Located on the Chajnantor plateau in Chile at an altitude of 5000 m, ALMA is finding and characterising the most distant and extreme galaxies, studying the properties of the interestellar medium in local galaxies, or exploring the chemistry of the Universe.

Launched on 14 May 2009, the Herschel Space Observatory was designed to observe a face of the Universe that had previously been hidden. Herschel observed radiation at FIR and submm wavelengths (70-500 μm), detecting dust obscured sources and cold objects that invisible to many other telescopes. Although the Herschel's observations finished on April 29 2013, the data collected will be producing revolutionary results over the next years.

Submm galaxies (SMGs) are the high redshift analogous to local ultraluminous infrared galaxies (ULIRGs) and are responsible for the bulk of the cosmic IR background. A percentage of SMGs are highly lensed, with amplification factors ranging 10-100×. The lensing boosts our effective sensitivity, which allows unprecedented follow-up and improved spatial resolution. This allows us to probe within SMGs on scales consistent with individual giant molecular clouds helping put constraints on theories of formation and evolution.

The physical conditions of molecular gas in galaxies, and the impact of star formation and active galactic nuclei (AGN) on these conditions and on the emergent stellar initial mass function (IMF), are overarching themes in astrophysics. We are entering an era where numerical simulations of turbulent molecular gas can be informed and constrained by observations of such gas. We investigate, theoretically and observationally, the impact of merger-driven star formation during a vital period in cosmic history, 1 < z < 3, when much of today's stellar mass was formed. It is here that we must study Larson's star-formation laws, and turbulence-regulated aspects of star formation, and look for possibly dramatic differences in the initial conditions of star formation, and the different IMF these may impose. These galaxies were significantly more gas-rich and turbulent than local starbursts, with different fragmentation histories and higher star-formation-rate densities (so more cosmic rays). They should yield cleaner signatures of a top-heavy IMF than local starbursts, where periods of ordinary star formation may have diluted such signatures. We will exploit strongly lensed starbursts to study powerful diagnostic rest-frame FIR cooling lines with Herschel’s Fourier Transform Spectrometer (FTS) and map velocity fields with the Jansky Very Large Array (JVLA), PdBI and ALMA, moving beyond studies of integrated galaxy properties to study the activity within starbursts on sub-kpc scales, distinguishing between fueling mechanisms and testing Larson's relations. At this level of sophistication, the analysis of the ISM at z > 1 begins to be comparable to that possible at z ~ 0. Abundances probed by multi-species, multi-J isotopologues and molecular diagnostics will reveal the dominant form of nucleosynthesis enriching their ISM, and gravo-turbulent magnetohydrodynamics (MHD) simulations of gas fragmentation in cosmic-ray-dominated regions will determine how turbulent energy injection affects merger-driven systems, producing IMF libraries as functions of ISM conditions to determine the cosmological consequences.